Avaliação dos solos Amazônicos: integração de dados multifontes para caracterização das condições edáficas

Abstract

The Amazon Basin is very diverse in soils. Such heterogeneity is due to the geological events that have occurred through time as well as the diversity of parent material, in which reminiscent of old rock fragments occur along with recent exposed rocks. With the strong weathering conditions from high temperatures, intense rainfall and biological activity, the structure of rocks and sediments are modified and release nutrients in the soil. Such elements are very important to sustain vegetation and largely control the dynamics of the forest. Efforts to determine the characteristics of Amazonian soils have been made in the last 50 years, but because of often different methodologies used to survey the soils, the existing information is usually of limited used for ecological research and studies of climate change impacts. Thus there is a perceived need to compile the existing databases and harmonize it using methods to standardize data to create a large scale, and methodology consistent Amazonian soil database. This was the objective of this work. To carry this out, I have compiled the three biggest soil databases for Amazonia: RADAMBRASIL, RAINFOR and WISE, which altogether add up to more than three thousand samples collected and analyzed for the region. The elements studied were carbon (C), nitrogen (N), potassium (K), magnesium (Mg), calcium (Ca) and aluminium (Al). All data was carefully filtered to exclude any samples which were located outside of pristine vegetation areas. Following that, a quadratic spline function was applied to the soil profiles to generate comparable depth to all databases. Once all samples were homogenized, an analysis of spatial variation of soil properties was performed. Such spatial representation of the dataset allowed interpreting the soil nutrient distribution across the basin and its relationship with parent material and geological age. Conclusion is that soil elemental concentration is a function of interactions between quality of parent material and geological age, with the least pedogenetic developed soils on better parent material having the highest elemental concentrations.